Parachute release mechanism



Aug. 1950 w. E. SIR] 2,517,511

PARACHUTE RELEASE MECHANISM Filed March '7, 1947 h 2 Sheets-Sheet 1INVEN TOR. fizz/#441? 5/6/ BYWaJeU V Aug. 1, 1950 w. E. SlRl 2,517,511

PARACHUTE RELEASE MECHANISM Filed March 7, 1947 2 Sheets-Sheet 2 INVENTOR. W/ZA MM 5 .f/E/

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Patented Aug. 1, 1950 E. 11Siri,1Be1'1keley, Califi, assignor to the 1United States of Americaas represented by the Secretary oi 1War 1Applidation March 7, 1947, Serial No. 733,133

1nism for automatically releasing a parachute at a selected altitude 1An object of the invention isto provide a device which may be used inconnectionwith asconventional parachute: pack and: which includes meansto pull the rip cordautorhatieally at a preselected altitude. 1 1 7 1Another object is to provide an improved parachute releasemechanism-which is simple-in construction, positive in ioperation andinexpensive to build. 1 1 1 More specifically an objector the inventionis to provide a device including a spring or other resilient means inwhich powermay be manually stored, together with a barometric device forreleasing said spring and performing work at a selected atmosphericpressure, and means for preselecting the pressure atwhich said releasingmeans will become operative. 1 K

Other objects, advantagesand meritoriousfeatures will become evident asthe: invention is here inafter described insdetail with. reference tothe drawing, wherein, 1 1

Fig. 1 is a top plan view of an embodiment of my invention withsthehousing cover removed to show the interior construction, a small portionof the housing being shown in section for clearness.

Figs. 2, 3, ands are sectional views taken at 2--2, 33 and 4-4,respectively, of Fig.1.

Fig. 5 is a sectional view taken at 5-5 ofFigl 2.

Like reference characters designate like parts throughout the severalviews.

Referring now to the draw-ing a housing H] 1 having a cover H isprovided externally with a hub l2, and, concentrically with said hubthere is a spring barrel l4 whichis threadedly secured in the housing at[6. A small. piston 18 isslidably fitted to a bore in the hub 12 and isbiased rightwise by an extension coil spring 20, the spring 20 beinganchored at the left hand end to the piston ill by a pin 2|, and at theright hand end by a pin 22 which passes through the slotted plug 24 andthrough the eye of the spring which lies in the slot. A cable 26 hasanend secured in the The piston l3 may be "drawnleftwise to its springloaded position manually by the cable 26, the free end of the cablebeing adapted for attachment to the device to be operated, in theinstant case, tothe rip-cord of aparachute.

Rotatably supportedi at its opposite ends in the housing Ill and cover His a latch shaft. 28 carrying an integral latch dog 301,the latchshaftllfl being adaptedxt be rocked clockwiseso aswto 1 slolaims. (01.244-4511) 1 2 1 1 swing the lower end of the dog 30 leftwise intoengagement with a flange 32 on the piston 18. A keyhole 3 4,1Fig. 2, inthe lower end of the shaft is provided, whereby a key may be insertedand the shaft 28 turned from outside the casing 110 until the dog 30engages theflange 32 whereby thelatch shaft 28 is biased foranticlockwise rotation. 1

Secured to and extending forwardlyfrom the upper end of the latch shaft28 is a latch arm 35.. Diagonally opposite the latch shaft 28 and havingits ends journaled in the housing It andcover H is a shaft 3 8:. A triplever is fast. at one end on the shaft 38, the otherwend beingadapted toswing into and out of. engagement with the swing? able end of the latcharm 3a. In the drawing the :swingable end of the trip lever 401 is shownat 42, Fig. 11, resting against the swingable end offthe latch arm 36thereby holding the latch arm 35 in the set position, 1

For the purpose of tripping the'trip 1 lever 4fl to release the latcharm 36, there islprovidedn linkage which includes a release arm 44whichis fast one shaft M3 the shaft having pivot bearing at the upperend in a bracket 48 extendingim oin the inner side-oi the housing ii]and, at thelower end in the end of anuadjustingscrew 50, Fig. 2. A stoppin 52 extends vertically from therelease arm at to limit its travel byengagement "with the latch arm 32. An extension spring it has -one endsecured to thefree end of the release arm M and the other end to thehousing to whereby the release arm 44 is biased iorclockwise rotationabout the pivot shaft 46. a Rigidly fixed to a block-55 on the undersideof thetrip lever 40 and extending substantially at right anglestherefrom is a trip lever operating arm 56. The two links 58 and 6fl 'ofa toggle iioint have their inner ends hinged together and to the righthand end of a pair of toggle operating 62. The leithand ends of thetoggle operating links 62 are hinged at 64 to the release arnifild. Theouter end of the toggle link 58 is hinged at 56 to the bracket 48,,whilethe outer end or the toggle link is hinged at 68 to the outer end of thetrip lever operating arm11'56.1 It is noted that if therelease arm M isrocked in11a clockwise direction about its shaft 46 by the spring, hingepoint 58 o f the operating arm 56 will be drawniorwardly by the togglelink 60, thereby rotating the trip lever 40 anticlockwise about itsshaft 38, whereby the free end oi1 the trip lever 40 at 42 is moved1-iorwardly out of engagement with the latch "arm 36 allowing the rlatcharmio be rotated anticlockwise by the spring 20 to the position whichopens the parachute.

A barometric device is provided which is operative to hold the latch arm36, trip lever 40, release arm 44 and operating linkage 5B, 58, 60, 62in the set position shown in the drawing whenever the device is above aselected altitude but becomes inoperative to hold these parts in the setposition whenever the device is below the said selected altitude.

The barometrically operative unit of the mechanism consists of a sealedbellows or multiple diaphragm l0 carried on the upper end of a screw 72.A nut 14 which is internally threaded to fit the screw 12 has a flangeit inside the housing and a hand knob It on the nut outside the housing,the hand knob being securedto the nut by a small screw 80 wherebyrotation of the hand knob 18 raises or lowers the bellows l8 bodily andexpansion or contraction of the fluid which is sealed in the bellows l0due to a change in altitude raises or lowers the upper ide of thebellows with respect to the lower side. The hand knob 18 has a skirt 82which carries indicia selectively registerable with correspondingindicia on the adjacent surfaces of the housing. The indicia is notshown in the drawing. The graduations are readable in terms of altitude.A leaf spring 84 supported on studs 85 prevents backlash in the altitudeselective part of the unit. A rod 86 is fast to the upper side of thebellows "it for movement therewith,

Rotatably supported in the housing in is a shaft 88. Shaft 88 carries alever system which includes a short arm 90 connected by a link 92 to theupper end of the rod 86, a spring arm 94 to the outer end of which oneend of an extension spring 96 is hooked, the other end being secured tothe housing I 0, and a trip arm 98, the free end of which props therelease arm 44 in the set'position shown when the device is above theselected altitude but withdraws and permits the release arm to rotateclockwise and trip the mechanism when the device is at or below theselected altitude.

Since the barometric unit is operative only to keep the mechanism in theset condition when the device is above a selected altitude, and it isdesirable that the device be put in the set condition when on the groundbefore going aloft, a manual means is provided for maintaining the setcondition until an altitude is reached which will cause the barometricunit to function. This manual means consists of a key 100 which isinsertable into an opening in the housing Hi, the key having an innerend which is adapted to slide alongside a dog 102 which is fast to theunderside of the release arm 44. When the key I00 is thus inserted inthe housing as shown, the release arm 44 will remain in the setcondition irrespective of the condition of the barometric unit.

When the term clockwise or anticlockwise is hereinafter employed unlessotherwise designated it shall be taken to mean clockwise oranticlockwise whenviewed as in Fig. 1.

The embodiment of the invention herein shown and described is to be usedsubstantially as follows:

Preferably, before the pilot goes aloft, he pulls the cable 26 to theleft, against the resistance of the spring '20, as far as it will go;inserts a key from below into the keyhole 34 and turns the latch shaft28 clockwise until the dog 38 is stopped by the piston flange 32;inserts thekey I which pushes against the dog I02 and thereby turns therelease arm anticlockwise into the set position shown andcoincidentally, by means of the toggle 58, 60, 62, draws the trip lever40 into the position shown where its end, props the latch arm 38 in theset position as at 42. The selector knob may now be set at the altitudeat which the device is to operate automatically to open a parachute, or,if he so desires, the flyer may wait to set the altitude knob untilafter he has gone aloft. In ether event, the device is ready to be takenaloft although the barometric device is not yet set to automaticallyrelease the device at the selected altitude.

When the device is taken aloft, the gradually decreasing pressure on theoutside of the bellows 10 causes it to raise the rod 86 and link 92,thereby turning the shaft 88 clockwise as viewed in Fig.3, thuspresenting the free end of the trip arm 98 against the free end of therelease arm 44. The altitude at which the, barometric device willfunction in this manner depends, of course. on the altitude to which theselector knob 18 is set. The key H18 may now be withdrawn or, at theoption of the flyer, it may be left inserted until just before he bailsout. ,When it is withdrawn, the device is still maintained in the setposition by engagement of the free end of the trip arm 98 with the freeend of the release arm 44 which condition will maintain until the devicedrops to an altitude where the increasing pressure on the outside of thebellows lohpulls down on the rod 86 and link 92 and thereby turns theshaft 88 and trip arm 98 anticlockwise, thus releasing the release arm44 for clockwise rotation, which, acting through the toggle 58, 60, 62disengages the end of the trip lever 40 from the end of the latch arm 36at 42, whereby the spring 20 may draw the piston l8 and the cable 26rightwise to pull the parachute rip cord and open the parachute as incurrent practice.

Having thus described an embodiment of the invention, I claim:

1. In a parachute release mechanism, the combination of a spring adaptedto be put under stress and automatically released to pull a parachuterip cord, latch means to hold said spring stressed, and a barometricdevice for releasing said latch means which consists of a multiplediaphragm expansible axially by reduction of the external pressurethereon, and adjustable means on one side of said diaphragm for movingsaid diaphragm bodily in the axial direction, and linkage on the otherside of said diaphragm operative to be moved by expansion of saiddiaphragm into a position for holding said latch means in the latchedcondition, and operative to be moved by contraction of said diaphragminto a position for unlatching said latch means. I

2. In a parachute release mechanism, the combination of a springadaptedto be put under stress and automatically released to operate aparachute release mechanism, latch means to hold said spring means inthe stressed condition, and a barometric device for releasing said latchmeans which consists of a hollow sealed bellows axially expansible byreduction of the external pressure thereon, an adjustable means on oneside of said bellows for bodily moving said bellows axially in eitherdirection, and linkage associated with the other side of said bellowsoperative to be moved by expansion of said bellows into a position forholding said latch means in the latched condition, and operative to bemoved by contraction of said bellows into a position to unlatch saidlatch means.

3. In a parachute release mechanism the combination of a spring adaptedto be manually put under stress and automatically released to pull aparachute rip cord, latch means to hold said spring stressed, and. abarometric device for releasing said latch means which consists of ahollow round bellows expansible axially by reduction of the externalpressure thereon, an adjustable means on one side of said bellows forbodily moving said bellows axially and linkage on the other side of saidbellows operative to be moved by axial expansion of said bellows into aposition for holding said latch means in the latched condition, and byaxial contraction of said bellows to release said latch means, andmanual means to maintain said latch means latched independent- 1y ofsaid barometric device.

4. Automatic parachute release mechanism which comprises, incombination, a resilient means adapted to be put under stress andautomatically released to operate a parachute, latch means to hold saidresilient means stressed, a latch release arm, a normally stressedresilient means for operating said latch release arm, power multiplyingleverage between said latch release arm and said latch means, wherebysaid normally stressed resilient means may trip said latch means, abarometric device for arresting operation of said latch release arm totrip said latch means, said barometric device consisting of a hollowsealed expansible means expansible by reduction of the external pressurethereon, an adjustable means on one side of said hollow sealedexpansible means for moving said hollow sealed expansible means bodily,and linkage on the other side of said hollow sealed expansible meansoperative to be moved, by expansion of said hollow sealed expansiblemeans, into engagement with 4 said latch release arm to prevent releaseof said latch means, and means adapted to engage said latch release armto prevent release of said latch means independently of said linkage.

5. Automatic parachute release mechanism which comprises, incombination, a heavy spring adapted to be manually put under stress andautomatically released to pull a parachute rip cord, latch means to holdsaid spring stressed, a latch release arm, a light spring for operatingsaid latch release arm, a power multiplying toggle joint between saidlatch release arm and said latch means through which said light springmay trip said latch means, a barometric device for arresting movement ofsaid latch release arm in a direction to trip said latch means, saidbarometric device consisting of a hollow sealed bellows axiallyexpansible by reduction of the external pressure thereon, an adjustablemeans on one side of said bellows for moving said bellows axial- 1y,linkageon the other side of said bellows operative to be moved, by axialexpansion of said bellows, into engagement with said latch release armto prevent operation of said latch release arm to release said latchmeans, and manual means adapted to engage said latch release arm toprevent movement thereof to thereby prevent release of said latch meansindependently of said linkage.

WILLIAM E. SIRI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,114,897 Bird Apr. 19, 19382,353,440 Bresee July 11, 1944 2,442,108 Zeller May 25, 1948 FOREIGNPATENTS Number Country Date 129,017 Great Britain July 10, 1919 435,267Great Britain Sept. 16, 1935 585,265 Great Britain Feb. 3, 1947

